Twitter stock has gotten too expensive, despite the company's darling status on Wall Street, Brian Wieser of Pivotal Research Group said Thursday.
"First of all, let me say Twitter is an amazing company—fantastic management, great ad products, wonderful traction," he said. "The problem is it's just simply overvalued. Now, to the extent that the stock will fall, eventually it will. It probably has to."
Wieser, senior research analyst with Pivotal, has a sell rating on shares of Twitter and a $30 price target.
(Read more: Jim Cramer: Is Twitter the next Amazon?)
Twitter stock closed at $55.33, up 3 percent for the day.
On CNBC's "Fast Money," Wieser said that the stock's pop on Twitter's unveiling of new features was unwarranted.
"This really illustrates how little investors who are buying into this understand the company, that they're bidding up the stock by 10 and 15 and 20 percent for a product announced in July," he said. "Most of the institutional investors I talk to understand that this is vastly overvalued. That doesn't mean there aren't people who aren't trading it, and I think there is a lot of short-covering going on because there were a lot of folks shorting it, fully agreeing with this notion that this is overvalued.
"Now, if you ... can convincingly tell me this company has, call it, $8 billion in revenue 2017, I get very comfortable with the valuation," he said. "But I get to about $4 [billion].
"I don't think that very many people are doing a lot of what we would call fundamental research. Let's put it that way."
Of the 20 Wall Street analysts covering Twitter, the average price target is $41.75.
Still, Wieser reiterated that his issue was not with Twitter itself.
"We all love the company. We all think it's a great business," he said. "It's just a question of what's an appropriate value."